PLATE TECTONICS

• History of Plate Tectonics and Continental Drift
• Abraham Ortelius (1596 ) - continents fit like jigsaw puzzle
• Edward Suess (1855)
• noted that Late Paleozoic plant fossils in India, Australia, Africa, Antarctica, and South America all look the same
• Gondwanaland
• Antonio Snider-Perlligrini (1858)
• wrote Creation and its mysteries revealed and showed (with maps) how the continents looked before they separated
• sited fossil evidence (North America and Europe)
• attributed the separation of the continents to the biblical deluge

• Frank B. Taylor (1908)
• pointed out that several geologic facts could be explained by continental drift
• suggested that the Mid-Atlantic Ridge marked the site along which an ancient continent broke apart to form the present-day Atlantic Ocean
• Alfred Wegner (1915)
• considered the father of Continental Drift
• wrote "The origin of the continents and oceans"
• drew series of maps that showed 3 stages of continental drift
• began with Pangea ("all land")
• believed that the continents (composed of light granitic rock) plowed through the denser rocks of the ocean floor
• driven by forces related to the rotation of the earth

• Arthur Holmes (1928) - provided a mechanism
• Thermal convection in the mantle
• Alexander du Toit (1937)
• wrote "Our wondering continents"
• noted climatological paradox of where coal beds and glacial deposits are today
• solved by moving Pangea to the south pole and North America to the equator and called the new landmass Laurasia

• Harry Hess (1960's)
• given credit for thermal convection along mid ocean ridges
• Early Evidence for Continental Drift
• continental fit
• rock sequences
• glacial evidence
• fossil evidence
• polar wandering
• Recent Evidence for Continental Drift
• seafloor spreading - 1960's
• ocean ridge systems
• deep-sea drilling
• magnetic anomalies
• age dating of rock
• Modern Plate Tectonics Theory
- the lithosphere is divided into plates, bounded by oceanic ridges, trenches, mountain ranges, and transform faults

• Types of Boundaries and features
• Divergent Plate Boundaries
• seafloor plate separation

• continental plate separation
• Convergent Plate Boundaries
• island arcs
• deep sea trenches
• Transform Boundaries
• Combinations
• Rates of Plate Motion
• paleomagnetics and anomalies
• magma generated at MOR become magnetized to the current orientation of the poles
• deep-sea drilling
• provided sediments from the ocean floors, some of which could be age dated either with fossils or with radiometric dating
• isochrons
• contours of equal time showing how much time has elapsed since the oceanic crustal rocks were first formed
• Geometry of Plate Motion
• transform boundaries
• indicates the direction of plate motion
• isochrons
• indicates the position of plates at past times
• satellite measurements of plate motions